Declining Contaminants in Bowhead Whales Offer Reassurance for North Slope
A multi year contaminant and nutrient monitoring program found that persistent organic pollutants in bowhead whale tissues have fallen to roughly one half to one quarter of 1990s levels, with many compounds continuing to decline. The findings matter to North Slope residents because they support the safety and nutritional value of subsistence foods while underscoring the need for continued monitoring and community informed management.
A long term monitoring effort led by the North Slope Borough Department of Wildlife Management and supported by the Alaska Eskimo Whaling Commission and the Whaling Captains Village Associations found substantial declines in persistent organic pollutants in bowhead whale tissues. Analysis comparing samples from 1997 to 2000 with samples from 2006 to 2015 showed blubber pollutant concentrations were markedly lower in the later period, and most blubber contaminants displayed significant declining trends between 2006 and 2015.
These trends follow patterns seen across the Arctic, with rates of decline similar to those reported for other Arctic biota. International policy action to restrict production and use of many persistent organic pollutants, including measures under the Stockholm Convention, has been identified as an effective driver of this decrease. The study also reported levels of PBDEs, a class of flame retardants, in bowhead tissues, finding most values below 3 ng per gram wet weight.
Researchers assessed a range of indicators relevant to both wildlife and human health. Blubber was tested for persistent organic pollutants, liver and kidney were analyzed for essential and non essential elements, and tissues were examined for structure consistent with disease. The body of evidence from these analyses indicates that contaminant levels are low and that associated risks to human health are very low. At the same time the work reinforced the nutritional importance of bowhead and other subsistence foods for people on the North Slope.
For local communities the results have immediate practical value. Bowhead whales are central to subsistence economy, food security, cultural practice, and intergenerational knowledge on the North Slope. Monitoring contaminant and nutrient levels supports science based guidance from local managers, hunters, and public health officials about the safety and benefits of traditional foods. The program provides baseline data to track long term trends and to inform public health recommendations and subsistence management decisions.
The research also highlights a gap in understanding. Baleen whales are less well studied than toothed whales, and continued sampling and analysis will be necessary to maintain confidence in the safety of subsistence harvests and to detect any emerging risks. Ongoing collaboration among local whaling organizations, community harvest monitors, and wildlife managers is essential to ensure the program reflects community priorities and supports equitable access to safe subsistence resources.
